The power of anomalies

What are anomalies all about? Are they just interesting quirks in science, or is there something more to them? If you believe the philosopher Thomas Kuhn, they are often the precursors of a revolution.

In the early 1960s Kuhn examined the history of science for clues to the nature of discovery. Scientists, he decided, work with one set of ideas about how the world is. There will be some evidence that doesn't fit, however. At first, Kuhn's study found, that evidence will be ignored or sabotaged. Eventually, though, the anomalies will pile up so high they simply cannot be ignored or sabotaged any longer. Then comes crisis, soon followed by the "paradigm shift" in which everyone gains a radically new way of looking at the world.

One example is the motions of the planets and stars as observed by the Greeks. The basic premise was that these objects revolved around the Earth. As observations got better and better, however, the astronomers had to repeatedly tweak their models of exactly how that revolving happened, adding layer upon layer of complication. It took a gargantuan effort to keep the theory together. Then, early in the 16th century, an astronomer called Nicolaus Copernicus recognised that Ptolemaic astronomers had created a monster, and set about working out a better system. When he published De Revolutionibus, it all suddenly became clear. The motions of stars and planets made sense – and worked out ever so simply – if everything was in fact revolving around the sun. After enormous efforts to maintain the existing paradigm, it finally shifted. More recent ideas, such as relativity, quantum theory, and the theory of plate tectonics arose in the same way.

Recognising and dealing with anomalies is a young man's game, Charles Darwin said. In On the Origin of Species, he wrote, "I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine," he says. Instead, he adds, he is looking with confidence to the future, to "young and rising naturalists, who will be able to view both sides of the question with impartiality.'

The question facing us now is, can science learn the lessons of the past? Can today’s scientists face up to, and deal with, today's anomalies? Or will the things that don't make sense always have to wait for a new generation of scientists?